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United States Patent |
5,183,024
|
Morita
,   et al.
|
February 2, 1993
|
Ignition device for internal combustion engine
Abstract
An ignition device for an internal combustion engine including: a DC power
source; a convertor for raising the voltage of the DC power source to a
predetermined voltage; a charge storing device arranged to be charged with
the output from the convertor; an ignition coil; an ignition signal
generator for generating an ignition signal in synchronization with the
rotation of the internal combustion engine; a switch which is switched on
in response to the ignition signal generated by the ignition signal
generator to discharge a charge stored in the charge storing device
through the ignition coil; and a controller for stopping the operation of
the convertor during a period in which the ignition signal is being
transmitted from the ignition signal generator.
Inventors:
|
Morita; Shingo (Himeji, JP);
Koiwa; Mitsuru (Himeji, JP)
|
Assignee:
|
Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
|
769318 |
Filed:
|
October 1, 1991 |
Foreign Application Priority Data
| Oct 04, 1990[JP] | 2-265121 |
| Oct 04, 1990[JP] | 2-265122 |
| Oct 05, 1990[JP] | 2-266357 |
Current U.S. Class: |
123/598; 123/605; 123/620 |
Intern'l Class: |
F02P 003/08 |
Field of Search: |
123/598,604,605,620,656
|
References Cited
U.S. Patent Documents
3838328 | Sep., 1974 | Lundy | 123/598.
|
4688538 | Aug., 1987 | Ward et al. | 123/598.
|
4696280 | Sep., 1987 | Niggemeyer | 123/598.
|
5074274 | Dec., 1991 | Okuda | 123/604.
|
Foreign Patent Documents |
51953 | Dec., 1978 | JP.
| |
38663 | Mar., 1982 | JP.
| |
140470 | Aug., 1983 | JP.
| |
Primary Examiner: Argenbright; Tony M.
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak and Seas
Claims
What is claimed is:
1. An ignition device for an internal combustion engine comprising:
a DC power source;
conversion means for raising the voltage of said DC power source to a
predetermined voltage;
charge storing means arranged to be charged with the output from said
conversion means;
an ignition coil;
ignition signal generating means for generating an ignition signal in
synchronization with the rotation of said internal combustion engine;
switching means which is switched on in response to said ignition signal
generated by said ignition signal generating means to discharge a charge
stored in said charge storing means through said ignition coil; and
control means for stopping the operation of said conversion means during a
period in which said ignition signal is being transmitted from said
ignition signal generating means,
wherein said conversion means includes an oscillating circuit, and a drive
circuit for amplifying an output signal transmitted from said oscillating
circuit, and
wherein said control means includes a detection circuit for detecting an
output of said ignition signal from said ignition signal generating means,
and a coincidence circuit responsive to an output from said oscillating
circuit and an output from said detection circuit for controlling said
drive circuit.
2. An ignition device for an internal combustion engine according to claim
1, wherein said conversion means further comprises a switching device
operated in response to an output signal transmitted from said drive
circuit and a transformer connected to said DC power source and
electrically turned on/off in accordance with the operation of said
switching device.
3. An ignition device for an internal combustion engine according to claim
1 wherein said switching means comprises a thyristor.
4. An ignition device for an internal combustion engine according to claim
2, wherein said coincidence circuit comprises an AND gate.
5. An ignition device for an internal combustion engine according claim 2
wherein said charge storing means include a capacitor connected to said
transformer.
6. An ignition device for an internal combustion engine comprising:
a DC power source;
conversion means for raising the voltage of said DC power source to a
predetermined voltage;
charge storing means arranged to be charged with the output from said
conversion means;
an ignition coil;
ignition signal generating means for generating an ignition signal in
synchronization with the rotation of said internal combustion engine;
switching means which is switched on in response to said ignition signal
generated by said ignition signal generating means to discharge a charge
stored in said charge storing means through said ignition coil;
discharge maintaining means for passing a discharge current through said
ignition coil for a predetermined time period after the discharge of a
charge stored in said charge storing means has been completed; and
control means for causing said conversion means to commence its operation
in synchronization with said ignition signal generated by said ignition
signal generating means.
7. An ignition device for an internal combustion engine according claim 6
wherein said conversion means includes an oscillating circuit, a drive
circuit for amplifying an output signal transmitted from said oscillating
circuit, a switching device operated in response to an output signal
transmitted from said drive circuit and a transformer which is connected
to said DC power source and which is electrically turned on/off in
accordance with the operation of said switching device.
8. An ignition device for an internal combustion engine according claim 6
wherein said switching means comprises a thyristor.
9. An ignition device for an internal combustion engine according claim 7
wherein said charge storing means includes a first capacitor and a second
capacitor respectively connected to said transformer.
10. An ignition device for an internal combustion engine according claim 9
wherein said discharge maintaining means includes an inductor which is
connected to a portion between said second capacitor and said ignition
coil.
11. An ignition device for an internal combustion engine comprising:
a DC power source;
a first inductor for raising the voltage of said DC power source to a
predetermined voltage;
charge storing means arranged to be charged with the voltage raised by said
first inductor;
an ignition coil;
ignition signal generating means for generating an ignition signal in
synchronization with the rotation of said internal combustion engine;
switching means which is switched on in response to said ignition signal
generated by said ignition signal generating means to discharge a charge
stored in said charge storing means through said ignition coil; and
discharge maintaining means for passing a discharge current through said
ignition coil for a predetermined time period after the discharge of a
charge stored in said charge storing means has been completed, wherein the
reference potential of each of said charge storing means and said
switching means is taken from the positive electrode of said DC power
source.
12. An ignition device for an internal combustion engine according claim 11
wherein said switching means comprises a thyristor.
13. An ignition device for an internal combustion engine according claim 11
wherein said charge storing means includes a first capacitor and a second
capacitor respectively connected to said first inductor.
14. An ignition device for an internal combustion engine according claim 13
wherein said discharge maintaining means includes a second inductor which
is connected to a portion between said second capacitor and said ignition
coil.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a condenser-discharge type ignition device
for an internal combustion engine.
2. Description of the Related Art
FIG. 6 illustrates a conventional ignition device for an internal
combustion engine. Referring to FIG. 6, a drive circuit 3 is connected to
an oscillating circuit 2. A transistor 4 serving as a first switching
device is connected to the drive circuit 3. An end portion of the primary
coil of a transformer is connected to the collector of the transistor 4.
The above-described oscillating circuit 2, the drive circuit 3, the
transistor 4 and the transformer 5 constitute a DC-DC converter. A
rectifying diode 6 is connected to the secondary coil of the transformer
5. A capacitor 8 is connected between the cathode of the rectifying diode
6 and ground. An end portion of the primary coil of an ignition coil 10 is
connected to a junction between the cathode of the rectifying diode 6 and
the capacitor 8. Furthermore, a thyristor 11 serving as a second switching
device is connected to a portion between another end portion of the
primary coil of the ignition coil 10 and the ground. Furthermore, an
ignition plug 15 is connected to the secondary coil of the ignition coil
10.
A trigger circuit 17 for generating a trigger signal in response to
ignition signal S.sub.2 is connected to an ignition signal generating
circuit 16 which generates the ignition signal S.sub.2 in synchronization
with the internal combustion engine. The trigger circuit 17 is connected
to the gate terminal of the thyristor 11. A battery 1 is connected to the
oscillating circuit 2, the drive circuit 3, another terminal of the
primary coil of the transformer 5, the ignition signal generating circuit
16 and the trigger circuit 17.
Then, the operation of the above-described conventional ignition device
will now be described. As shown in FIG. 7, the drive circuit 3 transmits a
drive signal to the transistor 4 in response to signal S.sub.1 transmitted
from the oscillating circuit 2. As a result, the transistor 4 is driven so
that the transformer 5 is electrically turned on/off. At this time,
primary current I.sub.1 generated in the primary coil of the transformer 5
is 7 converted into secondary current I.sub.2 of the transformer 5 so that
the capacitor 8 is charged via the diode 6. The capacitor 8 is charged to
a voltage level of V.sub.1 as shown in FIG. 7.
The ignition signal generating circuit 16 generates the ignition signal
S.sub.2 in synchronization with the ignition timing of the internal
combustion engine. In response to the ignition signal S.sub.2
thus-generated, the trigger circuit 17 transmits the trigger signal to the
gate terminal of the thyristor 11. When the thyristor 11 is
thus-triggered, the charge, which has been stored in the capacitor 8, is
discharged via the primary coil of the ignition coil 10 and the thyristor
11. At this time, discharge current I.sub.4 as shown in FIG. 7 is
introduced into the thyristor 11 from the capacitor 8. As a result, high
voltage is generated in the secondary coil of the ignition coil 10 so that
the ignition plug 15 is ignited.
However, if the secondary current I.sub.2 flows in the secondary coil of
the transformer 5 when the discharge current I.sub.4 is introduced into
the thyristor 11 from the capacitor 8, the secondary current I.sub.2 of
the transformer 5 is as well introduced into the thyristor 11 via the
diode 6 and the primary coil of the ignition coil 10. That is, total
current I.sub.5 passing through the thyristor 11 is the sum of the
discharge current I.sub.4 from the capacitor 8 and the secondary current
I.sub.2 of the transformer 5.
Therefore, although the total current I.sub.5 does not exceed a
predetermined value in a case where the timing at which the thyristor 11
is electrically turned on is, as shown in FIG. 7, different from the
timing at which the transformer 5 generates the secondary current I.sub.2
as at time t.sub.1 and t.sub.3, the total current I.sub.5 is excessively
enlarged in a case where the timing at which the thyristor 11 is
electrically turned on coincides with the timing at which the transformer
5 generates the secondary current I.sub.2 as at time t.sub.2. As a result,
there arises a problem that the overall apparatus size and the cost cannot
be reduced because the electric current capacity of the thyristor 11
cannot be reduced in order to protect the thyristor 11 from breakage.
FIG. 8 illustrates the structure of another conventional ignition device
for an internal combustion engine. The ignition device of this type
further comprises, in addition to the elements of the ignition device
shown in FIG. 6, a second rectifying diode 7 connected to the secondary
coil of the transformer 5. Furthermore, a second capacitor 9 is connected
to a portion between the cathode of the rectifying diode 7 and the ground.
In addition, a pulsating current preventing diode 12 is, in parallel,
connected to the primary coil of the ignition coil 10. An inductor 13 for
maintaining discharge time is connected to a portion between the cathodes
of the diodes 7 and 12. Furthermore, a diode 14 for maintaining the
discharge time is connected to a portion between the cathode of the diode
7 and the anode of the diode 12. The remaining elements are the same as
those for the ignition device shown in FIG. 6.
The operation of the ignition device of this type will now be described.
Similarly to the ignition device shown in FIG. 6, the second capacitor 9
is also charged via the diode 7 at the same time at which the capacitor 8
is charged. In this case, the capacitor 9 is charged with a voltage level
of V.sub.2 as shown in FIG. 9.
The ignition signal generating circuit 16 generates ignition signal S.sub.2
at the ignition timing of the internal combustion engine. In response to
the ignition signal S.sub.2, a trigger signal is transmitted from the
trigger circuit 17 to the gate terminal of the thyristor 11. When the
thyristor 11 is triggered, the charge, which has been stored in the
capacitor 8, is discharged via the primary coil of the ignition coil 10
and the thyristor 11. On the other hand, the charge stored in the
capacitor 9 is discharged via the inductor 13, the primary coil of the
ignition coil 10 and the thyristor 11. As a result, output voltage V.sub.3
and output current I.sub.3 as shown in FIG. 9 are generated in the
secondary coil of the ignition coil 10 so that the ignition plug 15 is
ignited.
At this time, a discharge maintaining current flows from the primary coil
of the ignition coil 10 via the diode 14 and the inductor 13. As a result,
the discharge made by the ignition plug 15 is maintained for
.DELTA.t.sub.1.
However, if the capacitors 8 and 9 are charged by energy supplied from the
DC-DC converter during the above-described time .DELTA.t.sub.1 in which
the discharge is maintained as at time t.sub.4, the above-described
discharge maintaining current is stopped, causing a problem to arise in
that the discharge is undesirably temporarily stopped.
Another problem takes place in that the size of the DC-DC converter cannot
be reduced because both of the above-described conventional ignition
devices similarly employ the transformer 5 in the DC-DC converter. In
addition, the charging efficiency of each of the capacitors 8 and 9
deteriorates due to the conversion efficiency of the primary and the
secondary sides of the transformer 5.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an ignition
device for an internal combustion engine capable of protecting its
thyristor from breakage while eliminating a necessity of using a thyristor
having a large current capacity.
Another object of the present invention is to provide an ignition device
for an internal combustion engine capable of preventing the undesirable
stop of discharge during the discharging operation performed by an
ignition plug.
Another object of the present invention is to provide an ignition device
for an internal combustion engine the size of which can be reduced and
which reveals an excellent charging efficiency.
According to one aspect of the present invention, there is provided an
ignition device for an internal combustion engine comprising: a DC power
source; conversion means for raising the voltage of the DC power source to
a predetermined voltage; charge storing means arranged to be charged with
the output from the conversion means; an ignition coil; ignition signal
generating means for generating an ignition signal in synchronization with
the rotation of the internal combustion engine; switching means which is
switched on in response to the ignition signal generated by the ignition
signal generating means to discharge a charge stored in the charge storing
means through the ignition coil; and control means for stopping the
operation of the conversion means during a period in which the ignition
signal is being transmitted from the ignition signal generating means.
According to another aspect of the present invention, there is provided an
ignition device for an internal combustion engine comprising: a DC power
source; conversion means for raising the voltage of the DC power source to
a predetermined voltage; charge storing means arranged to be charged with
the output from the conversion means; an ignition coil; ignition signal
generating means for generating an ignition signal in synchronization with
the rotation of the internal combustion engine; switching means which is
switched on in response to the ignition signal generated by the ignition
signal generating means to discharge a charge stored in the charge storing
means through the ignition coil; discharge maintaining means for passing a
discharge current through the ignition coil for a predetermined time
period after the discharge of a charge stored in the charge storing means
has been completed; and control means for causing the conversion means to
commence its operation in synchronization with the ignition signal
generated by the ignition signal generating means.
According to another aspect of the present invention, there is provided an
ignition device for an internal combustion engine comprising: a DC power
source; a first inductor for raising the voltage of the DC power source to
a predetermined voltage; charge storing means arranged to be charged with
the voltage raised by the first inductor; an ignition coil; ignition
signal generating means for generating an ignition signal in
synchronization with the rotation of the internal combustion engine;
switching means which is switched on in response to the ignition signal
generated by the ignition signal generating means to discharge a charge
stored in the charge storing means through the ignition coil; and
discharge maintaining means for passing a discharge through the ignition
coil for a predetermined time period after the discharge of a charge
stored in the charge storing means has been completed, wherein the
reference potential of each of the charge storing means and the switching
means is taken from the positive electrode of the DC power source.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram which illustrates the structure of an ignition
device for an internal combustion engine according to a first embodiment
of the present invention;
FIG. 2 is a timing chart which illustrates the operation of the first
embodiment;
FIG. 3 is a block diagram which illustrates the structure of a second
embodiment of the present invention;
FIG. 4 is a timing chart which illustrates the operation of the second
embodiment;
FIG. 5 is a block diagram which illustrates the structure of a third
embodiment of the present invention;
FIG. 6 is a block diagram which illustrates the structure of a conventional
ignition device for an internal combustion engine;
FIG. 7 is a timing chart which illustrates the operation of the device
shown in FIG. 6;
FIG. 8 is a block diagram which illustrates the structure of another
conventional ignition device for an internal combustion engine; and
FIG. 9 is a timing chart which illustrates the operation of the device
shown in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will now be described with
reference to the drawings.
Referring to FIG. 1, a drive circuit 3 is, via an AND or coincidence
circuit 19, connected to an oscillating circuit 2. A transistor 4 is
connected to the drive circuit 3. An end portion of the primary coil of a
transformer 5 is connected to the collector of the transistor 4. A
rectifying diode 6 is connected to the secondary coil of the transformer
5. A capacitor 8 is connected to a portion between the cathode of the
rectifying diode 6 and the ground. An end portion of the primary coil of
an ignition coil 10 is connected to the junction between the cathode of
the rectifying diode 6 and the capacitor 8. Furthermore, a thyristor 11 is
connected to a portion between another end portion of the primary coil of
the ignition coil 10 and the ground. An ignition plug 15 is connected to
the secondary coil of the ignition coil 10.
A trigger circuit 17 is connected to an ignition signal generating circuit
16, the trigger circuit 17 further being connected to the gate terminal of
the thyristor 11. An ignition signal detection circuit 18 for detecting
the output of an ignition signal is connected to the ignition signal
generating circuit 16, the output from the ignition signal detection
circuit 18 being connected to the AND circuit 19. The AND circuit 19
responds to the output S.sub.1 from the oscillating circuit 2 and the
output from the ignition signal detection circuit 18 so as to enable or
disable the drive circuit 3. A battery 1 is connected to the oscillating
circuit 2, the drive circuit 3, another terminal of the primary coil of
the transformer 5, the ignition signal generating circuit 16 and the
trigger circuit 17.
That is, the ignition device according to the first embodiment of the
present invention is constituted by arranging the conventional ignition
device shown in FIG. 6 in such a manner that: the ignition signal
detection circuit 18 is connected to the ignition signal generating
circuit 16; and the AND circuit 19 is inserted into the portion between
the oscillating circuit 2 and the drive circuit 3. As the ignition signal
detection circuit 18, an inverter circuit may be, for example, employed.
Then, the operation of the first embodiment of the present invention will
now be described with reference to a timing chart shown in FIG. 2. In
response to the signal S.sub.1 transmitted from the oscillating circuit 2,
the drive circuit 3 transmits a drive signal to the transistor 4. As a
result, the transistor 4 is driven so that the transformer 5 is
electrically turned on/off. At this time, primary current I.sub.1
generated in the transformer 5 is converted into secondary current I.sub.2
of the transformer 5. The secondary current I.sub.2 thus-generated as the
result of the conversion acts to charge the capacitor 8 to a charging
voltage level of V.sub.1 shown in FIG. 2 via the diode 6.
The ignition signal generating circuit 16 generates ignition signal S.sub.2
in synchronization with the ignition timing of the internal combustion
engine. In response to the ignition signal S.sub.2, the trigger circuit 17
transmits a trigger signal to the gate terminal of the thyristor 11. When
the thyristor 11 is thus-triggered, the charge, which has been stored in
the capacitor 8, is discharged via the primary coil of the ignition coil
10 and the thyristor 11. At this time, discharge current I.sub.4 is
introduced from the capacitor 8 into the thyristor 11 so that high voltage
is generated at the secondary coil of the ignition coil 10. As a result,
the ignition plug 15 is ignited.
When the ignition signal S.sub.2 is generated in the ignition signal
generating circuit 16, a detection signal is transmitted from the ignition
signal detection circuit 18 to the AND circuit 19. As a result of this,
the AND circuit 19 is electrically turned off so that output signal
S.sub.3 from the AND circuit 19 displays a waveform as shown in FIG. 2.
That is, the supply of the output from the AND circuit 19 to the drive
circuit 3 is restricted during the period in which the ignition signal
D.sub.2 is being generated. At this time, the primary current I.sub.1 and
the secondary current I.sub.2 of the transformer 5 are not generated.
Therefore, the secondary current I.sub.2 does not pass through the
secondary coil of the transformer at times t.sub.5, t.sub.6 and t.sub.7 at
each of which the discharge current I.sub.4 is introduced into the
thyristor 11 from the capacitor 8. Therefore, the total current I.sub.5
passing through the thyristor 11 is composed of only the discharge current
I.sub.4 transmitted from the capacitor 8. As a result, the breakage of the
thyristor 11 can be prevented while eliminating the necessity of using a
large current capacity thyristor 11.
A second embodiment of the present invention is shown in FIG. 3. The
ignition device for an internal combustion engine according to the second
embodiment is constituted by arranging the conventional ignition device
shown in FIG. 8 in such a manner that a synchronizing circuit 20 is
inserted into a portion between the ignition signal generating circuit 16
and the oscillating circuit 2. The above-described synchronizing circuit
20 causes the oscillating circuit 2 to commence the signal oscillating
operation in synchronization with the generation of the ignition signal
S.sub.2 in the ignition signal generating circuit 16.
Then, the operation of the second embodiment will now be described with
reference to a timing chart shown in FIG. 4. In response to signal S.sub.1
transmitted from the oscillating circuit 2, the drive circuit 4 transmits
a drive signal. As a result, the transistor 4 is driven so that the
transformer 5 is electrically turned on/off. At this time, the primary
current I.sub.1 generated in the primary coil of the transformer 5 is
converted into the secondary current I.sub.2 of the transformer 5. The
secondary current I.sub.2 thus-generated as a result of the conversion
acts to charge the two capacitors 8 and 9 via the diodes 6 and 7. As a
result, the capacitor 9 is charged with a charging voltage level of
V.sub.2 as shown in FIG. 4.
The ignition signal generating circuit 16 generates the ignition signal
S.sub.2 in response to the ignition timing of the internal combustion
engine. In response to the ignition circuit S.sub.2, the trigger signal 17
transmits a trigger signal to the gate terminal of the thyristor 11. When
the thyristor 11 is thus-triggered, the charge, which has been stored in
the capacitor 8, is discharged via the primary coil of the ignition coil
10 and the thyristor 11. On the other hand, the charge stored in the
capacitor 9 is discharged via the inductor 13, the primary coil of the
ignition coil 10 and the thyristor 11. As a result, the output voltage
V.sub.3 and the output current I.sub.3 as shown in FIG. 4 are generated in
the secondary coil of the ignition coil 10 so that the ignition plug 15 is
ignited.
At this time, a discharge maintaining current flows from the primary coil
of the ignition coil 10 via the diode 14 and the inductor 13. As a result,
discharge is maintained in the ignition plug 15 for only time
.DELTA.t.sub.2. According to this embodiment, time .DELTA.t.sub.3 in which
the signal S.sub.1 transmitted from the oscillating circuit 2 turns on the
transistor via the drive circuit 3 is made to be longer than the time
.DELTA.t.sub.2 in which the ignition plug 15 maintains its discharge
operation.
As is taken place at, for example, each time t.sub.8, t.sub.9 and t.sub.10
shown in FIG. 4, the signal oscillating operation performed by the
oscillating circuit 2 is commenced by the synchronizing circuit 20
whenever the ignition signal S.sub.2 is generated by the ignition signal
generating circuit 16. That is, the oscillating operation of the
oscillating circuit 2 is commenced in synchronization with the discharge
commencement of each of the capacitors 8 and 9. As described above, energy
is not further supplied from the DC-DC converter to the capacitors 8 and 9
in the time .DELTA.t.sub.2, in which the discharge is maintained because
the time .DELTA.t.sub.3, in which the transistor 4 is electrically turned
on, is longer than the discharge maintaining time .DELTA.t.sub.2.
Therefore, the undesirable temporary halt of the discharge during the
discharge operation of the ignition plug 15 due to the stop of the
discharge maintaining current can be prevented.
The ignition device for an internal combustion engine according to a third
embodiment of the present invention is shown in FIG. 5. The ignition
device according to this embodiment is constituted by arranging the
conventional ignition device shown in FIG. 8 in such a manner that: an
inductor 5A is employed in place of the transformer 5; and the reference
potential of each of the capacitors 8, 9 and the thyristor 11 is taken
from the positive electrode of the battery 1.
That is, an end portion of the inductor 5A is connected to the collector of
the transistor 4, while another end portion of the same is connected to
the positive electrode of the battery 1. The anode of each of the diodes 6
and 7 is connected to the collector of the transistor 4. The cathode of
each of the diodes 6 and 7 is, via capacitors 8 and 9, connected to the
positive electrode of the battery 1. The anode of the thyristor 11 is
connected to the primary coil of the ignition coil 10, while the cathode
of the same is connected to the positive electrode of the battery 1.
Since the terminals serving as the reference potentials of the capacitors
8, 9 and the thyristor 11 are, as described above, respectively connected
to the positive electrode of the battery 1, the introduction of an
electric current into the inductor 5A is prevented during the time in
which the thyristor 11 is being triggered.
Then, the operation of the third embodiment will now be described. In
response to the signal S.sub.1 transmitted from the oscillating circuit 2,
the drive circuit 3 transmits a drive signal to the transistor 4. As a
result, the transistor 4 is driven so that the inductor 5A is electrically
turned on/off. The energy generated in the inductor 5A at this time is
stored in the capacitors 8 and 9 via the diodes 6 and 7.
The ignition signal generating circuit 16 generates the ignition signal
S.sub.2 in synchronization with the timing of the internal combustion
engine. In response to the ignition signal S.sub.2, a trigger signal is
transmitted from the trigger circuit 17 to the gate terminal of the
thyristor 11. When the thyristor 11 is triggered, the charge, which has
been stored in the capacitor 8, is discharged via the primary coil of the
ignition coil 10 and the thyristor 11. On the other hand, the charge
stored in the capacitor 9 is discharged via the inductor 13, the primary
coil of the ignition coil 10 and the thyristor 11. As a result, high
voltage is generated in the secondary coil of the ignition coil 10 so that
the ignition plug 15 is ignited.
Since the ignition device according to the third embodiment is arranged in
such a manner that the inductor 5A is used in place of the DC-DC
converter, the size of the ignition device can be reduced and the charging
efficiency can be improved.
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